Apparatus for supporting and conducting electric current to a load



Dec. 13, 1960 F JONES ETAL 2,964,580

A. APPARATUS FOR SUPPORTING AND CONDUCTING ELECTRIC CURRENT TQ A LOAD Filed Nov. 20, 1957 4 Sheets-Sheet 1 vENToRs /I40 4. R/OE Dec. 13, 1960 Filed Nov 20, 1957 4 Sheets-Sheet 2 Y A. F. JONES ETAL 2,964,580 APPARATUS FOR SUPPORTING AND connucrrmc ELECTRIC CURRENT TO A LOAD INVENTORS Aer/I'M? E JONES G/VALD ,4. ,Q/CE

ATTORNEY Dec. 13, 1960 A. F. JONES ErAl. 2,964,580 APPARATUS FOR SUPPOR ND connucwmc ELE Filed Nov. 20, 1957 CTRIC CURRE A LOAD 4 Sheets-Sheet 3 INVENTORS AAVHZ/R f JONES DOA/4L0 4. R/CE Mme/v y Dec. 13, 1960 Filed Nov. 20, 1957 4 Sheets-Sheet 4 A. F. JONES EIAL 2,964,580 APPARATUS FOR SUPPORTING AND CONDUCTING ELECTRIC CURRENT TO A 1.01m

United States Patent APPARATUS FOR SUPPORTING AND CONDUCT- 'ING ELECTRIC CURRENT TO A LOAD.

Arthur Fredrick Jones, Massillon, and Donald A. Rice, Bolivar, Ohio, assignors to Republic Steel Corporation, Cleveland, Ohio, a corporation of New Jersey Filed Nov. 20, 1957, Ser. No. 697,702

14 Claims. (Cl. 13-16) This invention relates to improved apparatus for supporting a load and conducting electric current to the load. The apparatus described herein is intended to support and conduct current to a consumable electrode within an electric furnace, particularly a furnace of the type described in the copending application of Robert I. Garmy, Serial No. 698,256, filed November 22, 1957, and entitled Electric Furnace Utilizing Consumable Electrodes and Method of Operating Same. That furnace is designed particularly for forming ingots of metals such as titanium, zirconium and the like which are characterized by an extremely high melting point (e.g., in

the neighborhood of 3l40 F.-the melting point of titanium) and by high chemical activity at the melting point. However, that furnace has also been successfully used with other metals, e.g., steel, where an ingot of high purity was desired.

The presently preferred method of obtaining the 'hlg T: adjacent the fiangeis provided on each face with a horitemperature range necessary for melting of titanium and zirconium, which method is used in the furnace described in the copending application identified above, utilizes an electric arc. In that method, an electrode composed of the metal to be melted carries a heavy electrical current to support the arc and the electrode is fed into and consumed by the arc. Commonly, the electrodes are elongated and are suspended by one end and are fed downward. Under this method of creating heat and ultimately of melting the desired metal, some difficult problems are encountered. The electrode must be physically connected within the furnace to a supporting structure, and must be electrically connected to a power supply. The electrical connection, moreover, must be sufficiently conductive to carry a heavy electric current efiiciently within the high temperature environment. Since large currents are involved, the operation of elect rically connecting such electrodes to the power source has in the past been rather time-consuming.

Most successful commercial furnaces for this type of work, including the furnace for which the present invention is particularly intended, are batch-type furnaces, i.e., furnaces using electrodes of finite length. Such furnaces are required to be shut down after each electrode is consumed for the insertion of a new electrode. During that shut down, the ingot in the furnace must be removed so that the new electrode may be used to start a new ingot. Material from the new electrode would not unite homogeneously with the old ingot. The size of the ingot which is produced is therefore limited by the size of the electrode which can be fed. Since there is a commercial demand for larger ingots, and

. increasingly larger electrodes are required to produce the larger ingots, the problems of supporting such electrodes and supplying to them the larger electrical currents re- "ice such an electrode and support it as it is gradually lowered into the furnace. The clamp must also be capable of conducting electric current to the electrode. The second specific problem relates to the construction of means for supporting and conducting electrical current to the clamp.

An object of the present invention is to provide an improved apparatus for suspending a consumable electrode within a furnace of the type described and for making an electrical contact of high current carrying capacity with the electrode. I

Another object is to provide improved clamping means for gripping an electrode, which is simpler, more compact and easier to construct than existing clamping means.

Another object is to provide an improved clamp of the type described which may be easily and safety loaded supporting and conducting electric current to a clamp of the type described.

The foregoing and other objects of the invention are attained in the apparatus described herein, which includes a clamp and a clamp supporting structure.

The clamp includes a body of a generally T-shaped vertical cross-section having a central stem and an upper flange. The stem is polygonal, e.g., square or triangular, in horizontal cross-section, so that the stem has a plurality of flat vertical faces. The upper locality of the stern zontal semi-cylindrical groove for receiving a substantially cylindrical pivot pin which is fixed within the groove. A like plurality of clamp arms are provided, one for each vertical face of the stem, and are secured to the stem by screws, located somewhat below the pivot pins. Each arm extends below the stem. The upper end of each clamp arm is provided with a groove which is semi-cylindrical, and adapted to receive a pivot pin. The bottom end of the stem is adapted to abut the top end of the electrode to be supported, and the inside faces of the lower ends of the clamp arms are adapted to en gage abuttingly the sides of the electrode. Tightening of the screws forces the lower ends of the clamp arms against the electrode with substantial compressive force, and also tightens the upper ends of the clamp arm come pressively against the pivot pins. The stem of the clamp is somewhat smaller in effective diameter than the end of the electrode, so that when all the screws of all the clamp arms are tightened, the electrode is firmly gripped between the lower ends of the clamp arms, and the upper ends of the clamp arms firmly engage the pivot pins. These compressive engagements are strong enough to support the electrode, and have an electrical resistance low enough to conduct the arc current to the electrode. Means are provided upon the upper end of the body to. physically and electrically connect the clamp to movable suspension means and to an electrical power source.

The clamp supporting structure includes a hollow tube of electrically conductive material and through which a coolant is circulated. The lower end of the tube is attached to a contact plate adapted for bolting to the clamp. In accordance with the present invention, the connection between the lower end of the tube and the contact plate is formed by inserting a thick walledplug in the lower end of the tube and attaching-the plugto' the tube by means of welds of substantial area.- The outer surface of the plug is threaded with threadslof substantial depth, adapted to withstand" severe shear stresses. In this manner, the stresse's'are -taken bythe thick walled plug and are transferred to the relatively thin walled tube through the weld structures which have substantial strength.

Other objects and advantages of the invention will become apparent from the following description and claims taken together with the accompanying drawings.

In the drawings:

Fig. 1 is an elevational view of the upper portion of a furnace to which the present invention may be applied, showing the external electrode suspension and electric current supply mechanism;

Fig. 2 is a cross-sectional view taken through the upper end of the power tube in the furnace of Fig. 1;

Fig. 3 is a cross-sectional view taken through the lower end of the power tube and the electrode clamp in the furnace of Fig. 1;

Fig. 4 is a cross-sectional view similar to Fig. 2, but on a larger scale, showing an upper power tube connection constructed in accordance with the present invention;

Fig. 5 is a cross-sectional view similar to Fig. 4, but showing a lower power tube connection, constructed in accordance with the invention;

Fig. 6 is a cross-sectional view taken on the line VIVI of Fig. 5;

Fig. 7 is a view principally in elevation, showing one form of electrode clamp constructed in accordance with the invention, with some parts broken away and others shown in section;

Fig. 8 is a cross-sectional view taken on the line VIII-VIII of Fig. 7;

Fig. 9 is a cross-sectional view taken on the line IXIX of Fig. 7;

Fig. 10 is a cross-sectional view taken on the line X-X of Fig. 7;

Figs. 11 and 12 are views similar to Fig. 10, illustrating two modified forms of clamp structure;

Fig. 13 is a plan view of another modified form of clamp structure;

Fig. 14 shows in section, the upper end of an electrode receiving tube, with another modified form of clamp structure constructed in accordance with the present invention and resting on a saddle structure provided at the upper end of the tube;

Fig. 15 is a cross-sectional view taken on the line XVXV of Fig. 14;

Fig. 16 is a cross-sectional view taken on the line XVL-XVI of Fig. 14;

Fig. 17 is a plan view of the clamp of Fig. 14; and

Fig. 18 is a fragmentary horizontal cross-sectional view illustrating a modified clamp structure wherein the clamp grips the electrode corners.

Fig. 1

This figure illustrates the external electrode supporting and electric current supply apparatus of an electric furnace of the type described more completely in the Garmy application Serial No. 698,256, mentioned above. As shown in Fig. 1, there is provided at the upper end of the furnace a vertically elongated electrode receiving tube 1, having a cover plate 2. Mounted on the cover plate 2 is a seal structure 3. A power tube 4, which supports the electrode inside the tube 1, extends through the seal structure 3 and is attached at its lower end inside the furnace to a contact plate 5 (see Fig. 3). A clamp assembly 6, which may be any of the clamp assemblies described more completely below in connection with Figs. 7 to 17, is attached to the contact plate 5 by means of studs 7 and nuts 8. The upper-end of the tube 4 is carried by a coupling 9, shown in detail in Fig. 2, which is attached by means of a link 10 to a cross-head 11 which is suspended on two lead screws 12. The lead screws 12 are supported from their upper ends by means of combined thrust and guide bearings 13 which are mounted on a beam 14 supported at its. ends by columns 15in the form of steel H-beams. ColumnslS are supported on a plate 16 forming part of the carriage which moves along a pair of rails 17 mounted on beams 18 which may form a part of the building structure enclosing the furnace. The lead screws 12 may be rotated simultaneously by means of a motor (not shown) and suitable connecting mechanism, so as to raise and lower the cross-head 11 and the power tube 4, thereby raising; and lowering the electrode which is located inside the tube 1.

The power tube 4 is provided with an inner concentric coolant tube 19 which extends into the coupling 9, as best seen in Fig. 2. The lower end of the coolant tube 19 is spaced above the lower end of the power tube 4 by means of wings 20 welded to the lower end of the coolant tube. The coupling 9 is provided with coolant supply connections 21 and 22, so that a circulation of coolant fluid may be maintained through the coupling 21 down through the coolant tube 19, into the space below the open lower end of said coolant tube, up the space between the power tube 4 and the coolant tube 19 and out through the connection 22.

Clamped on the power tube 4 at its upper end is a bus bar 23 to which are attached cable tips 24 that conduct the heavy arc current to the bus bar 23 and thence to the power tube 4. The coupling 9 is connected to the link 10 by means of a ball and socket universal joint 25. A trunnion (not shown in detail) connects the upper end of link 10 to the crossbar 11.

The lower end of the power tube 4 is closed by means of a plug 26, which may be welded in place. The outer surface of the lower end of the tube 4 is threaded for insertion into a similarly threaded hole in the contact plate 5. A lock nut or jam nut 27 engages the threaded surface of the tube 4 and locks its connection with the contact plate 5.

It may be seen that the entire weight of the clamp assembly 6 and of the electrode 28 supported thereby is carried by the power tube 4 and by the threaded connections at the ends thereof. The power tube 4 is preferably made of copper, or a copper alloy selected for its strength and electrical conductivity characteristics, since it must carry an electrical current of the order of thousands of amperes.

The larger sizes of electrode and clamps apply severe stresses to the power tube. For example, electrodes weighing over 9,000 pounds are being used. Where such electrodes are used, the clamp structures employed to. hold them may Weight as much as 3,000 pounds, making a total load of over 12,000 pounds to be carried by thepower tube. Copper has sufiiciently high tensile strength so that a power tube may be readily constructed of the metal which will support the required weight. However, at the threaded connections at the ends of the power tube, the roots of the threads are stressed in shear. The shear strength ofcopper is somewhat lower than its tensile strength. Consequently, for the larger electroce and clamp structures something more than a simple threaded tube is needed for support. Such an improved support and current carrying coupling is illustrated in Figs. 4 to 6.

Figs. 4 to 6 These figures illustrate a power tube 30 which corresponds generally to the power tube 4 of Figs. 1 to 3. In the upper end of the tube 30, there is inserted a hollow plug 31, whose walls are substantially thicker than the walls of the tube 30. The outer surface of the upper end of the tube 30 is beveled and the plug 31 is provided, with a beveled shoulder which is opposed to the bevel on the upper end of the tube 30 and provides space for a strong load carrying fillet weld 32 extending about the entire periphery of the tube 30 and the plug 31. The tube 30 is also provided around its periphery with a plurality of openings 30a, which. are filled by plug welds 33. The primary function of: these latter Welds is to provide a low resistance path for current flow from plug 31 to tube 30, but they also provide a further load carrying con nection between the tube 30 and the plug 31. The plug 31 is threaded into the coupling 9 in a manner generally similar to the connection of the power tube 4. However, since the walls of the plug 31 are substantially thicker than the walls of the tube 30, appropriate threads can be used so as to carry the heavier loads. Furthermore, the load is transferred from plug 3-1 to tube 30 by a combination of shear and tensile stresses, so that tube 30 is nowhere stressed only in shear.

At the lower end of the tube 30, there is innserted a plug 34. The plug 34 corresponds to the plug 31, except that its lower end is closed by means of a disc 35, which may be welded in place. The lower end of plug 34 is threaded into the contact plate 5. A jam nut 27 is provided to hold the plug 34 tightly connected to the contact plate 5. A fillet weld 32 and plug welds 33 are provided to connect the plug 34 to the tube 30. These structures correspond to the similarly numbered structures at the upper end of the power tube.

Figs. 7 to These figures illustrate the clamp assembly 6 of Fig. 3 in greater detail. The clamp assembly 6 includes a body 36 which is generally T-shaped in vertical crosssection, having an upper flange 36a and a lower stem 36b (see Fig. 3). The stem 36b is rectangular in horizontal cross-section and has four vertical plane faces 36c on its sides. The upper end of each face 360 terminates at the lower edge of a substantially semi-cylindrical groove 36d formed in the clamp body 36. In each of the four grooves 36d, a copper pin 37 is fixed by means of one or more screws 38. The pins 37 serve as pivot pins and are substantially cylindrical. The heads of the screws 38 are countersunk within the pins 37.

Four clamp arms 39 are provided, one for each of the four faces 360 on the clamp stern. Screws 40 extend through the clamp arms 39 and are received in threaded apertures in the stem 36b. The lower ends of the clamp arms 39 extend below the bottom of the stem 36b and are adapted to engage the sides of the upper end of the electrode 28, as best seen in Fig. 3. The upper ends of the arms 39 are provided with semi-cylindrical recesses 39a which are adapted to engage the outer surfaces of the pivot pins 37.

When moving the clamp assembly 6 into engagement withan electrode 28, the screws 40 are all loosened so that the lower ends of all the clamp arms 39 can move freely down over the sides of the electrode 28. When the end of the electrode 28 reaches abutting engagement with the bottom of the stem 3612, then the screws 40 are tightened. Note that the dimensions of the electrode 28 are somewhat larger than the corresponding dimensions of the stem 36b, so that the inner surfaces of the clamp arms 39 are held spaced from the adjacent surfaces of the stem 36b. The screws 40 are then tightened, bringing the lower ends of the clamp arms 39 into firm abutting engagement with the sides of the electrode 28. At the same time, the recesses 39a at the upper ends of the clamp arms 39 are forced into tight abutting engagement with the pivot pins 37. During the tightening of the screws 40, the clamp arms 39 may pivot about the pins 37 as required to accommodate the movement of the clamp arms due to the tightening. Near the lower end of each of the clamp arms 39 there is provided a hole 3%. If desired, a hole can be drilled 'in the electrode in line with hole 39b, and a safety screw 29 inserted through both holes to supplement the frictional support afforded by the clamp arms 39. However, as a matter of actual practice, such screws are very seldom used, but the electrode is held sufficiently firmly by the frictional grip of clamp arms 39 alone.

The surfaces of the clamp arms facing the electrode may be variously contoured to accommodate the various electrode shapes. See for example, the contours of the clamp arms 41, 42, of Fig. 11 and the clamp arms 43, 44 of Fig, 12. Another possible alternative, illustrated in Fig. 18 is to have clamp arms 70 with internal angles 70a to grip the corners of electrodes 28 rather than the flat sides. It should be understood, however, that it is not necessary to have an exact or even a close matching of the clamp arm contours with the electrode contours. If there is an approximate matching, a sufficient frictional engagement can be forced between the clamp arms 39 and the electrode 28 to support it adequately.

The tight engagement between the clamp arms 39 and the electrode 28 provides an abutting contact, which serves as a part of the principal path of current flow to the electrode. The arms 39 also form a low resistance electrical contact with the pivot pins 37, which form another part of the principal path of flow of the arc current through the electrode. That principal path may be traced through the clamp body 36, the pins 37, the arms 39 and thence to the electrode 28. While some current flows through other paths, for example through the bolts 40 and also through the abutting contact between the end of the electrode and the bottom of the clamp body, nevertheless most of the current flows through the surfaces which are held in tight abutting engagement by the screws 40.

The upper surface of the clamp body 36 is provided with a ring of recesses to receive studs 7, which are permanently attached to the clamp body 36 by any well known method. The studs 7 cooperate with nuts 8 for attachment of the clamp body to the contact plate 5, as illustrated in Fig. 3. At the center of the top surface of the clamp body 36 there is'provided a somewhat larger recess 362, for receiving a ring pin such as that illustrated at 45 in Fig. 14. The ring pin 45 is utilized to receive the hook of a crane for transportation of the clamp assembly 6 and any electrode which may be clamped therein.

One or more horizontal holes 46 are provided through the flange portion 36a of the clamp body, for receiving a supporting rod such as that shown at 47 in Fig. 14, when the clamp is temporarily supported on the electrode tube 1 during the loading and unloading of the furnace. The flange 36a is made larger in horizontal cross-section than the stern 36b principally for the purpose of increasing the contact area between the upper end of the clamp body and the contact plate 5. The resistance of that electrical contact is thereby reduced.

The clamp body 36, pins 37, arms 39, and contact plate 5 may be constructed of any metal of high electrical conductivity. Usually steel or a copper alloy will be used, the choice being made dependent upon economic factors. The higher cost of copper must be balanced against the higher power loss in the steel.

50. The assembly 50 includes a clamp body generally indicated at 51. The principal difference between the clamp body 51 and the clamp body 36 is that the flange at the upper end of the clamp body 51 is substantially narrower than the flange on the clamp body 36. The corners of the stern portion of the clamp body 51 are cut away, as shown at 51a. A plurality of clamp arms 52 are provided, cooperating with the clamp body 56. It may be seen that these clamp arms occupy less of the total periphery of the clamp than do the clamp arms 39.

of Figs. 7 to 10. This clamp structure may be utilized when the electrode is somewhat lighter than the electrodes for which the clamp of Figs. 7 to 10 is intended.

Figs. 14 to 17 These figures illustrate amodified form of clamp assembly, generally indicated at 53 and comprisinga clamp body 54 whose stem portion is of substantially triangular cross-section, as best seen in Fig. 15, and three clamp arms 60,. The clamp assembly 53 is particularly suited for use in connection with an electrode of circular cross-section, such as is shown at 55.

There is shown in Fig. 14, a pair of wings 56, fixed on the upper end of the electrode receiving tube 1 and supporting a, pair of saddle plates 57. The saddle plates 57 are notched, in their upper surfaces, as shown at 57a to receive rods 47, which are insertable through holes 54a (see Fig. 17), which are drilled through the clamp body 54.

Those elements in Figs, 14 to 17 which correspond fully to their counterparts in the modifications previously described have been given the same reference numerals and, will not be further described.

Electrode changing operation In order to explain fully the advantages of the electrode supporting apparatus constructed in accordance with the invention, the operation of changing electrodes will now be described.

At the end of a run, the electrode clamp 6 in the furnace is supporting a short electrode butt. The electrode changing operation consists of removing this butt and replacing it with a fresh electrode for a new run.

After the arc current is shut off at the end of a run, the motor is operated to drive lead screws 12 in a direction to move cross head 11 upwardly, thereby carrying with it power tube 4 and the clamp assembly 6 with the electrode butt attached. When the contact plate engages the under side of cover 2, the cover is lifted from the end of the electrode tube 1. The upward movement of the electrode butt and its related parts is continued until horizontal holes 46, formed in clamp body 36 are at a level somewhat above the top of the electrode tube 1. Rods 47 (see Fig. 14) are then inserted through the holes 46. If saddles 57 are used, the electrode clamp is rotated by means of rods 47 until they are in line with the notches 57a in the saddles 57. The power unit mechanism is then driven to move the electrode clamp downwardly until the rods rest on the saddles, or on the electrode tube itself, if no saddles are provided. Nuts 8 are then removed. The motor is again operated to move the power tube 4 and its related parts upwardly, lifting the contact plate 5 free of the clamp assembly 6. The lift drive is then moved away. The clamp assembly 6 is now free overhead for access by a crane (not shown). Ring pin 45 is now inserted in threaded hole 36:: to receive the hook of the crane. The electrode butt and clamp are then lifted by the crane and taken to another location where the butt may be disassembled from the clamp.

The disassembly of the butt from the clamp and the insertion of a new electrode is an unusually simple and safe operation. Bolts 40 are loosened in any conventional manner, releasing the frictional grip of the clamp arms 39 upon the electrode butt. The electrode butt is then easily removed and the clamp is installed on a new electrode by moving it downwardly over the end thereof until the bottom of the clamp body 36 abuts the upper end of the electrode. Bolts 40 are then tightened and clamp arms 39 forced inwardly until their inner surface frictionally grips the upper portion of the new electrode.

The operation of disassembling the clamp 6 from the old butt and attaching it to a new electrode may be performed at a location remote from the furnace while the furnace is operating, so that a clamp and electrode are always ready for use in the furnace. The shut-down time of the furnace between runs is thereby decreased since it is not necessary to keep the furnace shut down while a high capacity electrical connection is made to the electrode structure itself.

The new electrode with clamp 6 assembled thereon may then be moved into place by the crane and lowered into the electr e tube un il h hole 46 in h l mp are slightly above the saddles 57. The rods 47 are then inserted into the holes and are aligned with the saddles, whereupon the crane lowers the clamp until the weight of the electrode and clamp is taken by rods 47. The crane is then unhooked and the ring 45 removed from clamp assembly 6.

The drive means is moved back into position and operated to lower power tube 4 and contact plate 5 until the latter comes into engagement with the electrode clamp assembly 6 and studs 7 are received through the apertures provided for them. The nuts 8 are then threaded upon the upper end of studs 9, fastening the contact plate to the electrode clamp. The drive mechanism is then run to lift the electrode slightly and take the weight from the rods 47. The rods are thereupon removed. The motor again runs to drive the electrode downwardly until the cover 2 again rests upon the top of electrode tube 1. The cover may be clamped in place by means of C clamps or any other suitable means.

The principal path of flow of electrical current from its power source to the electrode is through the cables and cable tip connectors 24, bus bar 23, power tube 4, contact plate 5, clamp body 36, pins 37, downwardly through the clamp arms 39 and thence through the sides of the electrode 28.

Electrical connection and disconnection of the electrode in the arc circuit is accomplished during loading and unloading of the furnace by the relatively simple mechanism described above involving the removal and replacement of the nuts 8 on studs 7. Thus the detachment of the electrode from its supporting structure also serves to disconnect it from the heavy current arc circuit.

While we have shown and described certain preferred embodiments of our invention, other modifications thereof will readily occur to those skilled in the art, and we therefore intend our invention to be limited only by the appended claims.

We claim:

1. Apparatus for supporting and conducting electric current to a consumable electrode, comprising a clamp body having one end constructed and arranged for electrically conductive contact with and support by an adjacent structure, said body having on its sides a plurality of plane faces distributed about the periphery of the body and parallel to the axis of the body and a plurality of contact elements projecting laterally adjacent the ends of said plane faces nearest said one end of the body, a plurality of clamp arms, one for each of said plane faces, each said clamp arm being longer than its associated plane face and having a first end portion constructed and arranged to abuttingly engage the adjacent contact element, a second end portion projecting beyond the end of the body opposite said one end and constructed and arranged to engage a side of an electrode of greater dimensions transverse to said axis than said clamp body when the electrode is aligned with said opposite end, and a central portion connecting said end portions and constructed and arranged to be positioned opposite the adjacent plane face on the clamp body, and means connecting said central portion and said clamp body and operable to move said central portion toward and away from said clamp body, said connecting means being operable to bring said first and second end portions into tight, abutting engagement with the associated contact element and electrode side, respectively, all said connecting means and arms cooperating to clamp the electrode between the clamp arms, and said arms cooperating to conduct electricity from the clamp body to the electrode.

2. Supporting and current conducting apparatus as defined in claim 1, in which said contact elements have substantially semi-cylindrical outer faces extending at right angles to said arms, and said first end portions of said clamp arms have substantially semi-cylindrical recesses fitting snugly against said outer faces, said outer :faces and said recesses cooperating to allow pivotal movement of said arms during tightening of said connecting means.

3. Supporting and current conducting apparatus as defined in claim 2, in which said contact elements comprise cylindrical pins, and means fixing said pins in semicylindrical recesses in said clamp body at the ends of said plane faces.

4. Supporting and current conducting apparatus as defined in claim 1, in which said second end portion has a plane clamping surface.

5. Supporting and current conducting apparatus as defined in claim 1, in which said second end portion has a cylindrical clamping surface.

6. Supporting and current conducting apparatus as defined in claim 1, in which said second end portion has two plane clamping surfaces joined at a dihedral angle.

7. Supporting and current conducting apparatus as defined in claim 6, in which said dihedral angle is an internal angle. a

8. Supporting and current conducting apparatus as defined in claim 6, in which said dihedral angle is an external angle.

9. Supporting and current conducting apparatus as defined in claim 1, in which said connecting means comprises, for each clamp arm, a bolt extending through an aperture in said arm and threadedly engaging an internally threaded hole in the clamp body.

10. Apparatus for supporting and conducting electric current to a consumable electrode, comprising a generally cylindrical contact plate of substantial diameter, means attached to one end of the contact plate for supporting it and supplying electric current to it, the other end of the plate having a flat surface, a clamp body having one end flat and constructed and arranged for electrically conductive contact with said other end of the contact plate, means for fastening said body and said plate together with said flat surfaces in abutting contact, said body having a stem of smaller dimensions transverse to the stem axis than said one end of said body, said stem having on its sides a plurality of plane faces distributed about the periphery of the stem and parallel to the axis of the stem and a plurality of contact elements projecting laterally adjacent the ends of said plane faces nearest said one end of the body, a plurality of clamp arms, one for each of said plane faces, each said clamp arm being longer than its associated plane face and having a first end portion constructed and arranged to abuttingly engage the adjacent contact element, a second end portion projecting beyond the end of the stern opposite said one end and constructed and arranged to engage a side of an electrode of greater dimensions transverse to the stem axis than said stem When the electrode is aligned with said opposite end, and a central portion connecting said end portions and having a plane surface constructed and arranged to be positioned opposite the adjacent plane face on the clamp body, and means connecting said central portion and said clamp body and operable to move said central portion toward and away from said clamp body, said connecting means being operable to bring said first and second end portions into tight, abutting engagement with its associated contact element and electrode side, respectively, all said connecting means and arms cooperating to clamp the electrode between the clamp arms, and said arms cooperating to conduct electricity from the clamp body to the electrode.

11. Apparatus for supporting and conducting electric current to a consumable electrode, comprising a vertically elongated, electrically conductive tube, a contact plate; a coupling for transmitting a tensile load between said plate and the lower end of said tube, said coupling comprising a plug substantially thicker than the walls of said tube, said plug having a first portion inserted in and closely fitting said end of said tube and a second portion projecting beyond said end, fillet weld means connecting the end of the tube to the plug, said tube having a plurality of spaced apertures adjacent said first portion of the plug, plug weld means filling said apertures, and external threads on said second portion of said plug and constructed and arranged for cooperating with an internally threaded aperture in one end of said plate; means supporting the upper end of the tube, means supplying electric current to the upper end of the tube, a clamp body having one end fiat and constructed and arranged for electrically conductive contact with the other end of the contact plate, means for fastening said body and said plate together with said flat surfaces in abutting contact, said body having a stem of smaller dimensions transverse to the stem axis than said one end of said body, said stem having on its sides a plurality of plane faces parallel to the axis of the stern and a plurality of contact elements projecting laterally adjacent the ends of said plane faces nearest said one end of the body, a plurality of clamp arms, one for each of said plane faces, each said clamp arm being longer than its associated plane face and having a first end portion constructed and arranged to abuttingly engage the adjacent contact element, a second end portion constructed and arranged to engage a side of an electrode of greater dimensions than said stem transverse to the stem axis, and a central portion connecting said end portions and having a plane surface constructed and arranged to be positioned opposite the adjacent plane face on the clamp body, and means connecting said central portion and said clamp body and operable to move said central portion toward and away from said clamp body, said connecting means being operable to bring said first and second end portions into tight, abutting engagement with its associated contact element and said electrode side, respectively, all said connecting means and arms cooperating to clamp the electrode between the clamp arms, and said arms cooperating to conduct electricity from the clamp body to the electrode.

12. Supporting and current conducting apparatus as defined in claim 11, including means for circulating fluid coolant through said tube, said plug being hollow and receiving a flow of said coolant, and means sealing the end of said plug in said plate aperture.

13. Supporting and current conducting apparatus as defined in claim 12, in which said means supporting the upper end of the tube comprises a second hollow plug similar to said first-mentioned plug, and a hollow pipe coupling into which said second plug is threaded, said pipe coupling comprising inlet and outlet means for said coolant circulating means.

14. Apparatus for supporting and conducting electric current to a consumable electrode, comprising an elongated, electrically conductive tube, a load carrying member, a coupling for transmitting a tensile load between said member and an end of said tube, said coupling comprising a plug substantially thicker than the walls of said tube, said plug having a first portion inserted in and closely fitting said end of said tube and a second portion projecting beyond said end, fillet weld means connecting the end of the tube to the plug, said tube having a plurality of spaced apertures adjacent said first portion of the plug, plug weld means filling said apertures, and external threads on said second portion of said plug and constructed and arranged for cooperation with an internally threaded aperture in said member.

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